1 . Field of the Invention
The present invention relates to a gallium nitride compound semiconductor which emits light in regions ranging from the visible spectrum to the ultraviolet range. In particular, the present invention relates to an electrode structure for a gallium nitride compound semiconductor light emission device having an excellent external emission efficiency.
2. Description of the Related Art
FIG. 13 is a plan view illustrating an exemplary structure of a conventional light emission device. As shown in FIG. 13, a p-type electrode 400 and an n-type electrode 100 for wire bonding are disposed in a diagonal arrangement. A peripheral electrode 200 is coupled to the n-type electrode 100, whereas a transparent electrode 300 is coupled to the p-type electrode 400. Among other structures, Japanese Laid-Open Patent Publication No. 10-163531 discloses a gallium nitride compound semiconductor light emission device structure such that the peripheral electrode 200 is provided at an outer periphery of a square-shaped light emission device, whereas the transparent electrode 300 is provided within an area surrounded by the peripheral electrode 200.
Generally, a component of light which is emitted by an active layer of a light emission device travels toward a substrate within the device, so as to be reflected therefrom and exit the device. In accordance with the aforementioned conventional light emission device, the n-electrode 100, which is formed in a peripheral portion of the face on which the p-type electrode 400 is provided (i.e., the face through which light is allowed to exit the light emission device), acts to shield the light reflected by the substrate from exiting the device. This results in a decrease in the amount of light which is generated by the light emission device, i.e., a decrease in the total light output power obtained from the light emission device.